KR20230128045A - Method for treating plastic pyrolysis oil including hydrogenation step - Google Patents

Abstract

The present invention relates to a process for treating plastic pyrolysis oil, comprising:
a) a hydrogenation step in which the feedstock is hydrogenated in the presence of at least hydrogen and at least one hydrogenation catalyst at an average temperature of 140 to 340° C. to obtain a hydrogenated effluent, wherein the outlet temperature of step a) is equal to the inlet temperature of step a) at least 15 °C higher than the hydrogenation step;
b) hydrotreating the hydrogenated effluent in the presence of at least hydrogen and at least one hydrotreating catalyst to obtain a hydrotreated effluent, wherein the average temperature of step b) is greater than the average temperature of step a) higher, the hydrotreating step;
c) separating the hydrotreated effluent in the presence of an aqueous stream at a temperature of 50 to 370° C. to obtain at least one gaseous effluent, an aqueous liquid effluent and a hydrocarbon-based liquid effluent.

Description

Method for treating plastic pyrolysis oil comprising a hydrogenation step

The present invention relates to a process for treating plastic pyrolysis oil to obtain a hydrocarbon-based effluent which can be upgraded by being introduced directly into a naphtha or diesel storage unit or introduced as a feedstock to a steam cracking unit. More specifically, the present invention relates to a method for treating a feedstock derived from pyrolysis of plastic waste to at least partially remove impurities that the feedstock may contain in relatively large amounts.

The plastic obtained in the collection and sorting channels may be subjected to a pyrolysis step, in particular to obtain a pyrolysis oil. These plastic pyrolysis oils are commonly burned to generate electricity and/or used as fuel in industrial boilers or city heating.

Another route to improving plastics pyrolysis oils is the use of these plastics pyrolysis oils as feedstock to steam cracking units to (re)produce olefins, which are constituent monomers of certain polymers. However, plastic waste is generally a mixture of several polymers, for example polyethylene, polypropylene, polyethylene terephthalate, polyvinyl chloride and polystyrene. Moreover, depending on the application, plastics may contain other compounds in addition to polymers, such as plasticizers, pigments, dyes or polymerization catalyst residues. Plastic waste may also contain small amounts of biomass originating from household waste, for example. The disposal of waste, in particular storage, mechanical treatment, sorting, pyrolysis on the one hand, and also storage and transport of pyrolysis oil on the other hand, can also lead to corrosion. As a result, the oil obtained from the pyrolysis of plastics waste is incompatible with the steam cracking unit or units located downstream of the steam cracking unit, in particular the polymerization process and the selective hydrogenation process, and often has a high content of many impurities, especially diolefins, metals, especially iron, silicon, or halogenated compounds, especially chlorine-based compounds, heteroelements such as sulfur, oxygen and nitrogen, and insoluble materials. These impurities can cause operability problems, in particular problems of corrosion, coking or catalyst deactivation, or alternatively compatibility problems in the application of the target polymer. The presence of diolefins may also lead to instability problems of pyrolysis oils, characterized by gums formation. Gum and insoluble materials that may be present in the pyrolysis oil may cause clogging problems in the process.

Moreover, during the steam cracking step, the yield of light olefins, particularly ethylene and propylene, sought for petrochemicals is highly dependent on the quality of the feedstock sent for steam cracking. The Bureau of Mines Correlation Index (BMCI) is often used to characterize hydrocarbon cuts. Developed for hydrocarbon-based products derived from crude oil, this index is calculated from measurements of density and average boiling point: 0 for linear paraffins and 100 for benzene. Thus, the values are all higher when the analyzed products have an aromatic condensation structure, and the naphthenes have intermediate BMCIs between paraffins and aromatics. Overall, the yield of light olefins increases when the paraffin content increases and when the BMCI decreases. Conversely, the yield of undesirable heavy compounds and/or coke increases as BMCI increases.

WO 2018/055555 proposes an overall process that can recycle plastic waste, which is very general and relatively complex, from the pyrolysis step of plastic waste to the steam decomposition step. The process of patent application WO 2018/055555 includes, inter alia, hydrotreating the liquid phase obtained directly from pyrolysis, preferably under very stringent conditions, in particular in terms of temperature, for example at temperatures from 260 to 300 ° C, separating the hydrotreating effluent, and then hydrodealkylating the separated heavy effluent, preferably at a high temperature, for example between 260 and 400°C.

Unpublished patent application FR 20/01758 describes a process for treating plastic pyrolysis oil, which process includes:

a) selectively hydrogenating olefins contained in the feedstock in the presence of hydrogen and a selective hydrogenation catalyst to obtain a hydrogenated effluent;

b) hydrotreating the hydrogenated effluent in the presence of hydrogen and a hydrotreating catalyst to obtain a hydrotreated effluent;

c) separating the hydrotreated effluent in the presence of an aqueous stream at a temperature between 50° C. and 370° C. to obtain a gaseous effluent, an aqueous liquid effluent and a hydrocarbon-based liquid effluent;

d) optionally fractionating all or part of the hydrocarbon-based effluent obtained from step c) to obtain at least two hydrocarbon-based streams, which may be a naphtha cut and a heavier cut, and a gas stream doing;

e) recovering the fraction of the hydrocarbon-based effluent obtained from separation step c) or the fraction and/or at least one of the hydrocarbon-based stream obtained from fractionation step d) into a selective hydrogenation step a) and/or hydrotreating step b) A recirculation step that includes a phase in which

According to application FR20/01.758, the selective hydrogenation step a) and the hydrotreating step b) are separate steps carried out under different conditions and in different reactors. Furthermore, according to application FR20/01.758, the selective hydrogenation step a) is carried out under mild conditions, in particular at temperatures between 100 and 250° C., which may lead to premature deactivation of the catalyst. Finally, according to application FR20/01.758, the hydrotreating step b) is generally carried out at a significantly higher temperature than the selective hydrogenation step a), in particular at a temperature of from 250 to 430 ° C, which is a device for heating between these two steps need

Accordingly, it would be advantageous to conduct the diolefin hydrogenation and part of the hydrogenation reaction, particularly the olefin hydrogenation and part of the hydrodemetallation reaction, particularly the retention of silicon, in one and the same step and at a temperature sufficient to limit deactivation of the catalyst.

This same step also makes it possible to benefit from the heat from the hydrogenation reaction, in particular from the hydrogenation of some of the diolefins, so that this step has an increasing temperature profile, and therefore a heat transfer between the catalyst section for hydrogenation and the catalyst section for hydrotreating. The need for devices for heating can be eliminated.

The present invention relates to a process for processing a feedstock comprising plastic pyrolysis oil comprising:

a) a hydrogenation step carried out in a hydrogenation reaction section to obtain a hydrogenated effluent, using at least one fixed bed reactor comprising n catalyst layers, wherein n is an integer greater than or equal to 1, each comprising at least one hydrogenation catalyst; The hydrogenation reaction section is fed with the feedstock and a hydrogen-containing gas stream, the hydrogenation reaction section having an average temperature between 140 and 400° C., 1.0 and 10.0 MPa abs. said hydrogenation step, wherein the temperature at the outlet of the reaction section of step a) is at least 15° C. higher than the temperature at ^the inlet of the reaction section of step a),

b) hydrogen carried out in a hydrotreating reaction section to obtain a hydrotreated effluent, using at least one fixed bed reactor comprising n catalyst beds, where n is an integer greater than 1, each containing at least one hydrotreating catalyst. As a treatment step, the hydrotreating reaction section is fed with at least the hydrogenated effluent obtained from step a) and the hydrogen containing gas stream, wherein the hydrotreating reaction section is fed with an average temperature between 250 and 430° C., between 1.0 and 10.0 MPa. abs. said hydrotreating step, wherein the average temperature of the reaction section of step ^b ) is higher than the average temperature of the hydrogenation reaction section of step a);

b') optionally carried out in the hydrocracking reaction section using at least one fixed bed comprising n catalyst beds, wherein n is an integer greater than or equal to 1, each containing at least one hydrocracking catalyst, which is then passed to the separation step c). a hydrocracking step to obtain a hydrocracked effluent, wherein the hydrocracking reaction section contains at least the hydrotreated effluent obtained from step b) and/or a compound having a boiling point greater than 175° C. obtained from step d) Cut and fed with a hydrogen containing gas stream, the hydrocracking reaction section has an average temperature between 250 and 450° C., 1.5 and 20.0 MPa abs. the hydrogen cracking step, wherein the hydrogen cracking step is used at a hydrogen partial pressure between 0.1 and 10.0 h ^-1 hourly space velocity;

c) receiving the hydrotreated effluent obtained from step b) or the hydrocracked effluent obtained from step b') and an aqueous solution, carried out at a temperature between 50 and 370°C, wherein at least one gas a separation step to obtain an effluent, an aqueous effluent and a hydrocarbon-based effluent;

d) optionally fractionating all or part of said hydrocarbonaceous effluent obtained from step c) to at least one gaseous effluent and at least one cut comprising compounds having a boiling point of less than or equal to 175°C and a boiling point greater than 175°C. A fractionation step to obtain one hydrocarbon-based cut containing a compound having

One advantage of the process according to the invention is the purification of at least some of the impurities in the oil obtained from the pyrolysis of plastic waste, which hydrogenates the plastic waste and includes it in particular in a fuel storage unit directly or in a steam cracking unit. By making it compatible with the processing of, it is possible to improve it, making it possible to obtain light olefins in increased yields, which can also be used as monomers, in particular in polymer production.

Another advantage of the present invention is to avoid the risk of clogging and/or corrosion of the treatment unit in which the process of the present invention is carried out, which risk is the presence of (often large amounts) diolefins, metals and halogenated compounds in the plastic pyrolysis oil. is aggravated by

Thus, the process of the present invention makes it possible to obtain a hydrocarbon-based effluent obtained from plastic pyrolysis oil that is at least partially free of the impurities of the starting plastic pyrolysis oil, thus in particular in the steam cracking unit and/or downstream of the steam cracking unit. In units located in the , especially in polymerization and hydrogenation units, these impurities limit operability problems such as corrosion, coking or catalyst deactivation problems. Removing at least some of the impurities from the oil obtained from the pyrolysis of plastic waste will also make it possible to increase the application range of the target polymer, and application incompatibilities are reduced.

According to one variant, the process comprises step d).

According to one variant, the process comprises step b′).

According to one variant, the amount of the gas stream comprising hydrogen that is fed to the reaction section of step a) is such that the hydrogen coverage is between 50 and 1000 Nm ³ of hydrogen per m ³ of feedstock (Nm ³ /m ³ ), preferably is such that 200 to 300 Nm ³ of hydrogen per m ³ of feedstock (Nm ³ /m ³ ).

According to one variant, the outlet temperature of step a) is at least 30° C. higher than the inlet temperature of step a).

According to one variant, at least one fraction of the hydrocarbon-based effluent obtained from the separation step c) or at least one fraction of the naphtha cut comprising compounds having a boiling point of less than 175 ° C obtained from the fractionation step d) It is sent to the hydrogenation step a) and/or to the hydrotreating step b).

According to one variant, at least one fraction of the cut comprising compounds having a boiling point greater than 175° C. obtained from said fractionation step d) is said hydrogenation step a) and/or said hydrotreating step b) and/or said It is sent to the hydrogenolysis stage b').

According to one variant, the process comprises a pretreatment step a0) of pretreating said feedstock comprising plastic pyrolysis oil, said pretreatment step being carried out upstream of said hydrogenation step a), a filtration step and/or electrostatic separation step and/or washing step with an aqueous solution and/or adsorption step.

According to one variant, the hydrocarbon-based effluent obtained from separation step c) or at least one of the two liquid hydrocarbon-based streams obtained from step d) has a temperature between 700 and 900° C. and between 0.05 and 0.3 MPa. sent wholly or partly to a steam cracking step e) carried out in at least one pyrolysis furnace at a relative pressure of

According to one variant, the reaction section of step a) uses at least two reactors operating in a permutable mode.

According to one variant, a stream containing amine is injected upstream of step a).

According to one variant, the hydrogenation catalyst comprises a support selected from alumina, silica, silica-alumina, magnesia, clay and mixtures thereof, and at least one group VIII element and at least one group VIB element, or at least one group VIII element. It includes a hydrogen-dehydrogenating function including

According to one variant, the hydrotreating catalyst comprises a support selected from the group consisting of alumina, silica, silica-alumina, magnesia, clay and mixtures thereof, and at least one Group VIII element and/or at least one Group VIB element. It contains a hydrogen-dehydrogenation functional group.

According to one variant, the process is carried out in the hydrocracking reaction section using at least one fixed bed comprising n catalyst beds, each comprising at least one hydrocracking catalyst, wherein n is an integer greater than or equal to 1, such that the separation step c ), wherein the hydrocracking reaction section contains cuts containing compounds having a boiling point above 175° C. obtained from step d) and containing hydrogen A gas stream is supplied and the hydrocracking reaction section is used at a temperature between 250 and 450° C., a hydrogen partial pressure between 1.5 and 20.0 MPa abs. and an hourly space velocity between 0.1 and 10.0 h ⁻¹ .

According to one variant, the hydrocracking catalyst comprises a support selected from halogenated alumina, a combination of boron and aluminum oxide, amorphous silica-alumina and zeolite, and at least one selected from chromium, molybdenum and tungsten, alone or as a mixture. a group VIB metal and/or a hydrogen-dehydrogenating functional group comprising at least one group VIII metal selected from iron, cobalt, nickel, ruthenium, rhodium, palladium and platinum.

The present invention also relates to products obtainable and preferably obtained through the process according to the present invention.

According to this variant, the product comprises, relative to the total weight of the product:

- a total content of metallic elements of less than or equal to 5.0 ppm by weight;

- a content of elemental iron of not more than 100 ppb by weight;

- a content of elemental silicon of not more than 1.0 ppm by weight;

- a sulfur content of less than or equal to 500 ppm by weight;

- a nitrogen content of less than or equal to 100 ppm by weight;

- a product comprising a content of elemental chlorine of less than or equal to 10 ppm by weight.

According to the present invention, the pressure is the absolute pressure (also denoted as abs.) and, unless otherwise indicated, is given in MPa absolute (or MPa abs.).

According to the present invention, the expressions "comprised of ... to ..." and "... to ..." are equivalent and mean that the limiting values of the interval are included in the value of the depicted range. If that is not the case and the limiting values are not included in the depicted range, such explanation will be provided by the present invention.

For the purposes of the present invention, various parameter ranges for a given stage, such as pressure ranges and temperature ranges, may be used alone or in combination. For example, for the purposes of the present invention, preferred ranges of pressure values may be combined with more preferred ranges of temperature values.

In the text that follows, specific and/or preferred embodiments of the present invention may be described. These may be implemented individually, or may be combined together without limitation of combination where technically possible.

In the following text, groups of chemical elements are given according to the CAS classification (CRC Handbook of Chemistry and Physics, published by CRC Press, editor-in-chief D.R. Lide, 81st edition, 2000-2001). For example, group VIII according to the CAS classification corresponds to metals in columns 8, 9 and 10 according to the new IUPAC classification.

Metal content is measured by X-ray fluorescence.

details

feedstock

According to the invention, “plastic pyrolysis oil” is advantageously an oil in liquid form at ambient temperature and is obtained from the pyrolysis of plastics, preferably plastic waste originating in particular from collection and sorting channels. It can also be obtained from the pyrolysis of worn tires.

These include in particular mixtures of hydrocarbon-based compounds, in particular paraffins, mono- and/or diolefins, naphthenes and aromatics. At least 80% by weight of these hydrocarbon-based compounds preferably have a boiling point of less than 700°C, preferably less than 550°C. In particular, depending on the origin of the pyrolysis oil, the oil comprises up to 70% by weight of paraffins, up to 90% by weight of olefins and up to 90% by weight of aromatics, the sum of paraffins, olefins and aromatics equaling 100% by weight of hydrocarbon-based compounds. is understood to be %.

The density of the pyrolysis oil measured at 15° C. according to the ASTM D4052 method is generally 0.75 to 0.99 g/cm ³ , preferably 0.75 to 0.95 g/cm ³ .

The plastic pyrolysis oil may further contain, and usually contains, impurities such as metals, in particular iron, silicon, or halogenated compounds, especially chlorinated compounds. These impurities are present in plastic pyrolysis oil at high content, for example up to 350 ppm by weight or up to 700 ppm by weight or even 1000 ppm by weight of halogen elements (especially chlorine) provided by halogenated compounds, up to 100 wt. ppm of metallic or semi-metallic elements. It may be present in ppm or even 200 ppm by weight. Alkali metals, alkaline earth metals, transition metals, post-transition metals and metalloids can resemble contaminants of metallic nature, referred to as metals or elemental metals or elemental semimetals. In particular, the metal or metal element or semi-metal element that may be included in the oil obtained from the pyrolysis of plastic waste includes silicon, iron or both of these elements. The plastic pyrolysis oil also contains other impurities, such as xenoelements, in particular provided by sulfur compounds, oxygen compounds and/or nitrogen compounds, generally in an xenoelement content of less than 10,000 ppm by weight, preferably less than 4000 ppm by weight. can do.

The feedstock of the process according to the invention comprises at least one plastic pyrolysis oil. The feedstock may consist exclusively of plastic pyrolysis oil(s). Preferably, the feedstock comprises at least 50% by weight, preferably 70% to 100% by weight of plastic pyrolysis oil, i.e. preferably 50% to 100% by weight, preferably 50% to 100% by weight relative to the total weight of the feedstock. 70% to 100% by weight of plastic pyrolysis oil.

The feedstock of the process according to the invention may comprise, in addition to the plastic pyrolysis oil(s), a conventional petroleum-based feedstock or a feedstock obtained from the conversion of biomass which is then co-processed with the plastic pyrolysis oil of the feedstock. can

A typical petroleum feedstock may advantageously be a cut or mixture of cuts of type naphtha, gas oil or gas oil under vacuum.

The feedstock obtained from the conversion of biomass is advantageously obtained from plant oils, oils from algae or algae oils, fish oils, consumed food oils, and fats of plant or animal origin, or mixtures of these feedstocks. can be chosen Plant oils may advantageously be wholly or partially raw or refined, and may include rapeseed, sunflower, soybean, palm, olive, coconut, coconut kernels, castor oil plant, cotton, peanut oil, linseed oil and sea kale oil. kale oil), and any oil derived, for example, from sunflower or from rapeseed by genetic modification or hybridization, this list is not limiting. The animal fat is advantageously selected from blues and fats consisting of residues from the food industry or derived from the catering industry. Frying oil, various animal oils such as fish oil, beef tallow or lard may also be used.

Feedstocks obtained from the conversion of biomass can also be obtained from processes for the thermal or catalytic conversion of biomass, such as oils produced from biomass, especially lignocellulosic biomass, together with various liquefaction methods such as hydrothermal liquefaction or pyrolysis. It can be selected from the originating feedstock. The term "biomass" is a material derived from a recently living organism, including plants, animals and their by-products. The term “lignocellulosic biomass” refers to biomass derived from plants and their by-products. Lignocellulosic biomass is composed of carbohydrate polymers (cellulose, hemicellulose) and aromatic polymers (lignin).

Feedstocks obtained from the conversion of biomass may also advantageously be selected from feedstocks obtained from the paper industry.

Plastic pyrolysis oil may be obtained from thermal, catalytic pyrolysis treatment, or may be produced by hydropyrolysis (pyrolysis in the presence of a catalyst and hydrogen).

preprocessing (optional)

Said feedstock comprising plastics pyrolysis oil may advantageously be pretreated in an optional pretreatment step a0), prior to the hydrogenation step a), in order to obtain a pretreated feedstock which is fed to step a).

This optional pretreatment step a0) makes it possible to reduce the amount of contaminants present in the feedstock comprising plastics pyrolysis oil, in particular the amount of iron and/or silicon and/or chlorine. Thus, the optional pretreatment step a0) of the feedstock comprising plastics pyrolysis oil is carried out in particular when the feedstock contains more than 10 ppm by weight of metal elements, in particular more than 20 ppm by weight and more particularly more than 50 ppm by weight of metal elements, in particular in the feedstock. is advantageously performed when contains more than 5 ppm by weight of silicon, more particularly more than 10 ppm by weight or even more than 20 ppm by weight of silicon. Likewise, the optional pretreatment step a0) of the feedstock comprising plastics pyrolysis oil is advantageously carried out in particular when the feedstock comprises more than 10 ppm by weight of chlorine, in particular more than 20 ppm by weight and more particularly more than 50 ppm by weight of chlorine.

The optional pretreatment step a0) may be carried out by any method known to a person skilled in the art to reduce the amount of contaminants. This may in particular include a filtration step and/or an electrostatic separation step and/or a washing step with an aqueous solution and/or an adsorption step.

Optional pretreatment step a0) is advantageously carried out at a temperature of from 0 to 150° C., preferably from 5 to 100° C., and at a pressure of from 0.15 to 10.0 MPa abs, preferably from 0.2 to 1.0 MPa abs.

According to one variant, the optional pretreatment step a0) is adsorption operated in the presence of at least one adsorbent, preferably of the alumina type, having a specific surface area of at least 100 m ² /g, preferably of at least 200 m ² /g. performed in the section. The specific surface area of the at least one adsorbent is advantageously less than or equal to 600 m ² /g, in particular less than or equal to 400 m ² /g. The specific surface area of the adsorbent is the surface area measured by the BET method, i.e. nitrogen according to the standard ASTM D 3663-78 established from the Brunauer-Emmett-Teller method described in the periodical The Journal of the American Chemical Society, 60, 309 (1938). is the specific surface area determined by adsorption. Advantageously, the adsorbent comprises less than 1% by weight of elemental metals, and is preferably free of elemental metals. The term "metal elements of adsorbents" should be understood to refer to elements of groups 6 to 10 of the Periodic Table of the Elements (new IUPAC classification). The residence time of the feedstock in the adsorbent section is generally between 1 and 180 minutes.

Said adsorption section of optional step a0) comprises at least one adsorption column, preferably at least 2 adsorption columns comprising said adsorbent, preferably from 2 to 4 adsorption columns. If the adsorption section comprises two adsorption columns, one mode of operation may be what is termed “swing” operation according to dedicated terminology, where one of the columns is on-line, i.e. in service, and the other column is in reserve. am. When the adsorbent in the online column is consumed, the column is sequestered while the pre-column is placed online, i.e. in service. And the spent adsorbent can be regenerated in situ and/or replaced with fresh adsorbent so that the column containing it can be put back online as soon as the other columns are isolated.

Another mode of operation is to have at least two columns operating in series. When the adsorbent in the column arranged in the head is consumed, this first column is isolated and the spent adsorbent is either regenerated in situ or replaced with fresh adsorbent. And the column comes back online in its last position. This mode of operation is known as the permutable mode, or PRS (interchangeable reactor system), or "lead and lag" according to proprietary terminology. The combination of at least two adsorption columns results in possible and potentially rapid poisoning and/or clogging of the adsorbent due to the combined action of metal contaminants, diolefins, gums obtained from diolefins and insoluble materials that may be present in the plastic pyrolysis oil to be treated. enable you to overcome This means that the presence of at least two adsorption columns advantageously facilitates replacement and/or regeneration of the adsorbent without shutdown of the pretreatment unit, or even without shutdown of the process, thus reducing the risk of clogging and thus reducing the cost of the unit due to clogging. This is because it makes it possible to avoid shutdowns, control costs and limit the consumption of adsorbents.

According to another variant, the optional pretreatment step a0) is carried out in the section for washing with an aqueous solution, for example water, or an acidic or basic solution. This washing section may include a device for contacting the feedstock with an aqueous solution and separating the phases to obtain a pretreated feedstock on the one hand and an aqueous solution comprising impurities on the other hand. Among these devices there may be, for example, stirred reactors, decanters, mixer-decanters and/or co-current or counter-current washing columns.

The optional pre-treatment step a0) may optionally also be fed at least a fraction of the recycle stream advantageously obtained from step d) of the process as a mixture with or separately from the feedstock comprising plastics pyrolysis oil. .

Thus, the optional pretreatment step a0) makes it possible to obtain a pretreated feedstock which feeds the hydrogenation step a).

Hydrogenation step a)

According to the present invention, the process is carried out in a hydrogenation reaction section using at least one fixed bed reactor comprising n catalyst beds, where n is an integer greater than 1, each containing at least one hydrogenation catalyst to form a hydrogenated effluent. a hydrogenation step a) to obtain, said hydrogenation reaction section being fed with said feedstock and a hydrogen containing gas stream, said hydrogenation reaction section having an average temperature between 140 and 400° C., between 1.0 and 10.0 MPa abs. and at an hourly space velocity between 0.1 and 10.0 h-1, the outlet temperature of the reaction section of step a) is at least 15° C. higher than the inlet temperature of the reaction section of step a).

Step a) is capable of carrying out hydrogenation of diolefins and olefins at the beginning of the hydrogenation reaction section, while increasing the temperature at the outlet of the reaction section of step a) to be at least 15° C. higher than the inlet temperature of the reaction section of step a). It is carried out in particular under hydrogen pressure and temperature conditions that allow for a temperature profile. In practice, the amount necessary to allow hydrogenation of at least a portion of the diolefins and olefins present in the plastic pyrolysis oil, hydrodemetallization of at least a portion of the metals, in particular retention of silicones, and also conversion (to HCl) of at least a portion of the chlorine of hydrogen is injected. Hydrogenation of diolefins and olefins thus makes it possible to avoid or at least limit the formation of "gums" that can prevent the reaction section of hydrotreating step b), i.e. the polymerization of diolefins and olefins and thus the formation of oligomers and polymers. let it In parallel with the hydrogenation, the hydrodemetallization and in particular the retention of silicon during step a) makes it possible to limit the catalyst deactivation of the hydrotreating reaction section of step b). Furthermore, the conditions of step a), in particular the temperature and its increasing profile, make it possible to convert at least part of the chlorine.

Therefore, temperature control is important at this stage and must satisfy the antagonistic constraint. On the other hand, the temperature at the inlet and throughout the hydrogenation reaction section must be sufficiently low to permit hydrogenation of diolefins and olefins at the start of the hydrogenation reaction section. On the other hand, the inlet temperature of the hydrogenation reaction section must be sufficiently high to avoid deactivation of the catalyst. Since the hydrogenation reaction, especially for the hydrogenation of some of the olefins and diolefins, is highly exothermic, an increasing temperature profile is observed in the hydrogenation reaction section. This higher temperature at the end of the section makes it possible to carry out dehydrogenation and dechlorination reactions. Thus, the outlet temperature of the reaction section of step a) is at least 15° C. higher, preferably at least 25° C. higher, particularly preferably at least 30° C. higher than the inlet temperature of the reaction section of step a).

The temperature difference between the inlet and outlet of the reaction section of step a) is the optional injection of any gaseous (hydrogen) cooling stream or liquid cooling stream (e.g. recirculation of the stream originating from step c) and/or d)) is compatible with

The temperature difference between the inlet and outlet of the reaction section of step a) is entirely due to the exothermic nature of the chemical reaction carried out in the reaction section and is therefore compatible without the use of heating means (oven, heat exchanger, etc.).

The inlet temperature of the reaction section of step a) is 135 to 385 °C, preferably 210 to 335 °C.

The outlet temperature of the reaction section of step a) is 150 to 400 °C, preferably 225 to 350 °C.

According to the present invention, it is advantageous to carry out the hydrogenation of the diolefin and part of the hydrotreating reaction in one and the same step at a temperature sufficient to limit the deactivation of the catalyst of step a) as indicated by a decrease in diolefin conversion. This same step can also benefit from the heat from the hydrogenation reaction, in particular the hydrogenation of some of the olefins and diolefins, so that this step has an increasing temperature profile and thus a catalyst section for hydrogenation and a catalyst for hydrotreating The need for devices for heating between sections can be eliminated.

The reaction section advantageously has an average temperature (or WABT as defined below) of 140 to 400° C., preferably 220 to 350° C., particularly preferably 260 to 330° C., in the presence of at least one hydrogenation catalyst, 1.0 to 400° C. a hydrogen partial pressure of 10.0 MPa abs, preferably from 1.5 to 8.0 MPa abs, and an hourly space velocity (HSV) of from 0.1 to 10.0 h ^-1 , preferably from 0.2 to 5.0 h ^-1 , very preferably from 0.3 to 3.0 h ^-1 ) to carry out hydrogenation.

According to the present invention, the “average temperature” of the reaction section corresponds to the weight-average bed temperature (WABT) according to a dedicated term well known to those skilled in the art. The average temperature is advantageously determined as a function of the catalytic system used, the apparatus and its configuration. Average temperature (or WABT) is calculated in the following way:

Where, Tinlet: temperature of the effluent at the inlet of the reaction section, Toutlet: temperature of the effluent at the outlet of the reaction section.

Hourly space velocity (HSV) is defined herein as the ratio of the hourly volumetric flow rate of a feedstock comprising optionally pretreated plastic pyrolysis oil to the volume of catalyst(s).

Hydrogen coverage is the volumetric flow rate of hydrogen taken under standard temperature and pressure conditions relative to the volumetric flow rate of a "fresh" feedstock, i.e., the feedstock to be treated, optionally pretreated, without taking into account any recycled fraction, at 15°C. is defined as the ratio of (normal m3 of H ₂ per m3 of feedstock (expressed in Nm3)).

The quantity of the gas stream comprising hydrogen (H2) which is fed to the reaction section of step a) is advantageously such that the hydrogen coverage is between 50 and 1000 Nm3 of hydrogen per m3 of feedstock (Nm3/m3), preferably the feedstock. 50 to 500 Nm3 of hydrogen per m3 (Nm3/m3), preferably 200 to 300 Nm3 of hydrogen per m3 of feedstock (Nm3/m3). In practice, the amount of hydrogen required to allow at least part hydrogenation of diolefins and olefins and at least part dehydrogenation of metals, in particular retention of silicon, and also at least part conversion of chlorine (conversion to HCl) is described in FR20/01.758. is greater than the amount of hydrogen required to make it possible to carry out only hydrogenation of diolefins as described above.

The hydrogenation reaction section of step a) is fed with said feedstock comprising at least plastic pyrolysis oil, or the pretreated feedstock obtained from optional pretreatment step a0), and a gas stream comprising hydrogen (H2). Optionally, the reaction section of step a) can likewise be fed at least with a fraction of the recycle stream advantageously obtained in step c) or optional step d).

Advantageously, the reaction section of step a) comprises 1 to 5 reactors, preferably 2 to 5 reactors, particularly preferably 2 reactors. The advantage of a hydrogenation reaction section comprising several reactors consists in enabling an optimized treatment of the feedstock and at the same time reducing the risk of clogging of the catalyst bed(s) and thus avoiding shutdown of the unit due to clogging.

According to one variant, these reactors operate in exchangeable mode, also known as “PRS” or otherwise “lead and lag” for exchangeable reactor systems. The combination of at least two reactors in PRS mode makes it possible to isolate one reactor, drain spent catalyst, recharge the reactor with fresh catalyst, and return the reactor to service without stopping the process. PRS technology is described in particular in patent FR2681871.

According to one particularly preferred variant, the hydrogenation reaction section of step a) comprises two reactors operating in exchangeable mode.

Advantageously, reactor inserts, for example of filter plate type, can be used to prevent clogging of the reactor(s). An example of a filter plate is described in patent FR3051375.

Advantageously, the hydrogenation catalyst comprises a support, preferably a mineral support, and a hydrodehydrogenation functional group.

According to one variant, the hydrodehydrogenation function comprises in particular at least one element of group VIII, preferably selected from nickel and cobalt, and at least one element of group VIB, preferably selected from molybdenum and tungsten. . According to this variant, the total content expressed as oxides of metal elements from groups VIB and VIII is preferably from 1% to 40% by weight, preferably from 5% to 30% by weight, relative to the total weight of the catalyst. . When the metal is cobalt or nickel, the metal content is indicated by CoO and NiO, respectively. When the metal is molybdenum or tungsten, the metal content is indicated by MoO ₃ and WO ₃ , respectively.

The weight ratio expressed as metal oxide between Group VIB metal(s) to Group VIII metal(s) is preferably 1 to 20, preferably 2 to 10.

According to this variant, the reaction section of step a) contains, for example, from 0.5% to 12% by weight of nickel, preferably from 1% to 10% by weight of a support, preferably a mineral support, preferably an alumina support. % of nickel (expressed as nickel oxide NiO relative to the weight of the catalyst), and between 1% and 30% by weight of molybdenum, preferably between 3% and 20% by weight of molybdenum (with respect to the weight of the catalyst molybdenum oxide MoO ₃ Expressed as) and a hydrogenation catalyst comprising.

According to another variant, the hydrodehydrogenation function comprises, preferably consists of, at least one element of group VIII, preferably nickel. According to this variant, the content of nickel oxide is preferably from 1% to 50% by weight, preferably from 10% to 30% by weight relative to the weight of the catalyst. Catalysts of this type are preferably used in reduced form on a mineral support, preferably an alumina support.

The support for the hydrogenation catalyst is preferably selected from alumina, silica, silica-alumina, magnesia, clay and mixtures thereof. The support may contain a dopant compound, in particular boron oxide, in particular an oxide selected from boron trioxide, zirconia, ceria, titanium oxide, phosphorus pentoxide and mixtures of these oxides. Preferably, the hydrogenation catalyst comprises an alumina support optionally doped with phosphorus and optionally with boron. If phosphorus pentoxide P ₂ O ₅ is present, its concentration is less than 10% by weight relative to the weight of the alumina, advantageously at least 0.001% by weight relative to the total weight of the alumina. If boron trioxide B ₂ O ₃ is present, its concentration is less than 10% by weight relative to the weight of the alumina, advantageously at least 0.001% by weight relative to the total weight of the alumina. The alumina used may be, for example, γ (gamma) or η (eta) alumina.

The hydrogenation catalyst is, for example, in the form of an extrudate.

Very preferably, step a) also comprises, in addition to the hydrogenation catalyst(s) described above, on an alumina support, less than 1% by weight of nickel and at least 0.1% by weight of nickel, expressed as nickel oxide NiO, relative to the weight of said catalyst. step a, preferably comprising 0.5% by weight of nickel, and less than 5% by weight of molybdenum expressed as molybdenum oxide MoO ₃ and at least 0.1% by weight of molybdenum, preferably 0.5% by weight of molybdenum, relative to the weight of the catalyst. ) can use one or more hydrogenation catalysts used in This catalyst, which is not highly loaded with metals, can preferably be placed upstream or downstream of the hydrogenation catalyst(s) described above.

The hydrogenation step a) makes it possible to obtain a hydrogenated effluent, ie an effluent with a reduced content of olefins, in particular diolefins and metals, in particular silicon. The content of impurities, in particular diolefins, of the hydrogenated effluent obtained at the end of step a) is reduced compared to the content of the same impurities, in particular diolefins, contained in the feedstock of the process. Hydrogenation step a) generally makes it possible to convert at least 40%, preferably at least 60% of the diolefins contained in the initial feedstock and at least 40%, preferably at least 60% of the olefins. Step a) also makes it possible to at least partially remove other contaminants, for example silicon and chlorine. Preferably, at least 50%, more preferably at least 75% of the chlorine and silicon of the initial feedstock are removed during step a). The hydrogenated effluent obtained at the end of hydrogenation step a) is preferably passed directly to hydrotreating step b).

Hydrotreating step b)

According to the present invention, the treatment process is carried out in a hydrotreating reaction section, using at least one fixed bed reactor comprising n catalyst layers, each containing at least one hydrotreating catalyst, wherein n is an integer greater than or equal to 1, resulting in a hydrotreated product. a hydrotreating step b) obtaining an effluent, wherein the hydrotreating reaction section is fed with at least the hydrogenated effluent obtained from step a) and a gas stream containing hydrogen, the hydrotreating reaction section being fed with 250 and 430 Average temperature between °C, 1.0 and 10.0 MPa abs. and an hourly space velocity between 0.1 and 10.0 h ⁻¹ , wherein the average temperature of the reaction section of step b) is higher than the average temperature of the hydrogenation reaction section of step a).

Advantageously, step b) embodies hydrotreating reactions well known to those skilled in the art, more particularly hydrotreating reactions such as hydrogenation of aromatics, hydrodesulfurization and hydrodeazotization. In addition, hydrogenation and also hydrodemetallization of the olefins and the remaining halogenated compounds continue.

The hydrotreating reaction section is advantageously implemented at a pressure equivalent to that used in the reaction section of hydrogenation step a), but at a higher average temperature than that of the reaction section of hydrogenation step a). Thus, the hydrotreating reaction section advantageously has an average hydrotreating temperature of 250 to 430° C., preferably 280 to 380° C., a hydrogen partial pressure of 1.0 to 10.0 MPa abs., and 0.1 to 10.0 h ⁻¹ , preferably 0.1 to 5.0 h ⁻¹ , preferably 0.2 to 2.0 h ⁻¹ , preferably 0.2 to 1 h ⁻¹ . The hydrogen coverage in step b) is advantageously between 50 and 1000 Nm 3 of hydrogen per m 3 of the fresh feedstock fed in step a), preferably between 50 and 500 N per m 3 of the fresh feedstock fed in step a). m3 of hydrogen, preferably 100 to 300 Nm3 of hydrogen per m3 of fresh feedstock supplied to step a). The definitions of mean temperature (WABT), HSV and hydrogen coverage correspond to those described above.

The hydrotreating reaction section is fed at least, advantageously into the first catalyst bed of the first operational reactor, with the hydrogenated effluent obtained from step a) and a gaseous stream comprising hydrogen. Optionally, the reaction section of step b) can likewise be fed at least with a fraction of the recycle stream advantageously obtained in step c) or optional step d).

Advantageously, said step b) is carried out in a hydrotreating reaction section comprising at least one, preferably 1 to 5 fixed bed reactors comprising n catalyst layers, where n is greater than 1, preferably 1 to 10 , preferably an integer from 2 to 5, wherein the layer(s) each contain at least one, preferably no more than 10 hydrotreating catalysts. If the reactor comprises several catalyst layers, ie at least 2, preferably 2 to 10, preferably 2 to 5 catalyst layers, the catalyst layers are preferably arranged in series in the reactor.

If step b) is carried out in a hydroprocessing reaction section comprising several reactors, preferably two reactors, these reactors can be operated in series and/or parallel and/or exchangeable (or PRS) mode and/or swing mode. it can work The various alternative modes of operation, PRS (or lead and lag) mode and swing mode are well known to those skilled in the art and are advantageously defined herein.

In another embodiment of the invention, the hydrotreating reaction section comprises a single fixed bed reactor containing n catalyst beds, where n is an integer greater than or equal to 1, preferably from 1 to 10, preferably from 2 to 5.

In one particularly preferred embodiment, the hydrogenation reaction section of step a) comprises two reactors operating in exchangeable mode, followed by the hydrotreating reaction section of step b) comprising a single fixed bed reactor.

Advantageously, the hydrotreating catalyst used in step b) may be selected from the known hydrodemetallization, hydrotreating or silicon scavenging catalysts, especially used for the treatment of petroleum cuts, and combinations thereof. Known hydrodemetallization catalysts are, for example, those described in patents EP 0113297, EP 0113284, US 5221656, US 5827421, US 7119045, US 5622616 and US 5089463. Known hydrotreating catalysts are, for example, those described in patents EP 0113297, EP 0113284, US 6589908, US 4818743, or US 6332976. Known silicon scavenging catalysts are, for example, those described in patent applications CN 102051202 and US 2007/080099.

In particular, the hydrotreating catalyst comprises a support, preferably a mineral support, and at least one metal element having a hydrodehydrogenation functional group. The metal element having a hydrodehydrogenation functional group is preferably at least one Group VIII element selected from the group consisting of nickel and cobalt, and/or at least one Group VIB element preferably selected from the group consisting of molybdenum and tungsten. advantageously contains the element The total content, expressed as oxides of metal elements from groups VIB and VIII, is preferably from 0.1% to 40% by weight, preferably from 5% to 35% by weight, relative to the total weight of the catalyst. When the metal is cobalt or nickel, the metal content is indicated by CoO and NiO, respectively. When the metal is molybdenum or tungsten, the metal content is indicated by MoO ₃ and WO ₃ , respectively. The weight ratio expressed as metal oxide between Group VIB metal(s) to Group VIII metal(s) is preferably 1.0 to 20, preferably 2.0 to 10. For example, the hydrotreating reaction section of step b) of the process contains from 0.5% to 10% by weight of nickel, preferably from 1% to 8% by weight of nickel expressed as nickel oxide NiO, relative to the total weight of the hydrotreating catalyst. of nickel, and 1.0% to 30% by weight of molybdenum, preferably 3.0% to 29% by weight of molybdenum, expressed as molybdenum oxide MoO, relative to the total weight of the hydrotreating catalyst, a mineral support, preferably on an alumina support.

The support for the hydrotreating catalyst is advantageously selected from alumina, silica, silica-alumina, magnesia, clay and mixtures thereof. The support may also contain a dopant compound, in particular boron oxide, in particular an oxide selected from boron trioxide, zirconia, ceria, titanium oxide, phosphorus pentoxide and mixtures of these oxides. Preferably, the hydrotreating catalyst comprises an alumina support, preferably an alumina support doped with phosphorus and optionally with boron. If phosphorus pentoxide P ₂ O ₅ is present, its concentration is less than 10% by weight relative to the weight of the alumina, advantageously at least 0.001% by weight relative to the total weight of the alumina. If boron trioxide B ₂ O ₃ is present, its concentration is less than 10% by weight relative to the weight of the alumina, advantageously at least 0.001% by weight relative to the total weight of the alumina. The alumina used may be, for example, γ (gamma) or η (eta) alumina.

The hydrotreating catalyst is, for example, in the form of an extrudate.

Advantageously, the hydrotreating catalyst used in step b) of the process has a specific surface area of at least 250 m 2 /g, preferably at least 300 m 2 /g. The specific surface area of the hydrotreating catalyst is advantageously 800 m 2 /g or less, preferably 600 m 2 /g or less, and particularly 400 m 2 /g or less. The specific surface area of the hydrotreating catalyst is measured by the BET method, i.e. according to the standard ASTM D 3663-78 established from the Brunauer-Emmett-Teller method described in the periodical The Journal of the American Chemical Society, 60, 309 (1938). is the specific surface area determined by nitrogen adsorption. This specific surface area makes it possible to further improve the removal of contaminants, especially metals such as silicon.

According to another aspect of the present invention, the hydrotreating catalyst as described above also comprises at least one organic compound containing oxygen and/or nitrogen and/or sulfur. Such catalysts are often denoted by the term "additivated catalyst". In general, the organic compound has one or more functional groups selected from carboxyl, alcohol, thiol, thioether, sulfone, sulfoxide, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea, and amide functional group. compounds containing chemical functional groups or compounds containing furan rings or other sugars.

Advantageously, the hydrotreating step b) allows hydrogenation of at least 80%, preferably all, of the olefins remaining after hydrogenation step a), but also removes other impurities present in the feedstock, such as aromatics, metal compounds, sulfur. compounds, nitrogen compounds, halogen compounds (particularly chlorine compounds) and oxygen compounds. Preferably, the nitrogen content in the product of step b) is less than 10 ppm by weight. Step b) may also make it possible to further reduce the content of contaminants, such as the content of metals, in particular the silicon content. Preferably, the metal content in the product of step b) is less than 10 ppm by weight, preferably less than 2 ppm by weight and the silicon content is less than 5 ppm by weight.

Hydrogenolysis step (optional) b')

According to one variant, the process of the invention comprises a hydrocracking step carried out immediately after the hydrotreating step b) or after the fractionation step d) in a hydrocarbon-based cut (diesel cut) comprising compounds having a boiling point above 175 ° C. b').

Advantageously, step b′) implements a hydrogenolysis reaction well known to the person skilled in the art, and more particularly, heavy compounds, for example compounds with a boiling point greater than 175° C., are obtained from step b) or are fractionated in step d) It can be converted into compounds with a boiling point below 175 °C contained in the hydrotreated effluent separated during the process. Other reactions may follow, such as hydrogenation of olefins or aromatics, hydrodemetallization, hydrodesulphurization, hydrodeazotization, etc.

Compounds with boiling points greater than 175° C. have high BMCIs and contain more naphthenic, naphtheno-aromatic and aromatic compounds compared to lighter compounds, leading to higher C/H ratios. This high ratio is a cause of coking in the steam cracker, and therefore a steam cracking furnace dedicated to this cut is required. When it is desired to minimize the yield of these heavy compounds (diesel cuts) and maximize the yield of light compounds (naphtha cuts), these compounds can be at least partially converted to light compounds by hydrocracking, which is generally steam It is a preferred cut for disassembly units.

Thus, the process of the present invention is carried out in the hydrocracking reaction section, using at least one fixed bed comprising n catalyst beds, each comprising at least one hydrocracking catalyst, wherein n is an integer greater than 1, so that the fractionation step d) a hydrocracking step b′) obtaining a hydrocracked effluent which is sent to the hydrocracking reaction section, wherein the hydrocracking reaction section contains at least the hydrotreated effluent obtained from step b) and/or the 175 effluent obtained from step d). A gas stream containing hydrogen and a cut containing compounds having a boiling point above °C is fed, the hydrocracking reaction section having an average temperature between 250 and 450 °C, 1.5 and 20.0 MPa abs. and at hourly space velocities between 0.1 and 10.0 h ^-1 .

Thus, the hydrocracking reaction section is 1.5 to 20.0 MPa abs., preferably 2 to 18.0 MPa abs., at an average temperature of 250 to 480°C, preferably 320 to 450°C. at a hydrogen partial pressure of 0.1 to 10.0 h ⁻¹ , preferably 0.1 to 5.0 h ⁻¹ , preferably 0.2 to 4 h ⁻¹ , and at an hourly space velocity (HSV). The hydrogen coverage in step c) is advantageously between 80 and 2000 Nm 3 of hydrogen per m 3 of the fresh feedstock fed in step a), preferably between 200 and 1800 N per m 3 of the fresh feedstock fed in step a). cubic meter of hydrogen. The definitions of mean temperature (WABT), HSV and hydrogen coverage correspond to those described above. Advantageously, said hydrocracking reaction section is operated at a pressure equivalent to that used in the reaction section of hydrogenation step a) or hydrotreating step b).

Advantageously, step b′) is carried out in a hydrocracking reaction section comprising at least one, preferably 1 to 5 fixed bed reactors comprising n catalyst layers, n being at least 1, preferably 1 to 10 , preferably an integer from 2 to 5, wherein the layer(s) each contain at least one, preferably no more than 10 hydrocracking catalysts. If the reactor comprises several catalyst layers, ie at least 2, preferably 2 to 10, preferably 2 to 5 catalyst layers, the catalyst layers are preferably arranged in series in the reactor.

The hydrotreating step b) and the hydrocracking step b') may advantageously be carried out in the same reactor or in different reactors. When these are carried out in the same reactor, the reactor comprises several catalyst layers, the first catalyst layers comprising the hydrotreating catalyst(s) and the subsequent catalyst layers comprising the hydrocracking catalyst(s).

The hydrocracking step can be carried out in one step (step b')) or in two steps (steps b') and b")). If carried out in two steps, the effluent obtained in the first hydrocracking step b') Separation of the water can be carried out to obtain a cut comprising compounds having a boiling point above 175° C. during steps c) and d) (diesel cut), which cut is different from the first hydrocracking reaction section b′) into a second hydrocracking stage b″) comprising a second hydrocracking reaction section. This configuration is particularly suitable where it is desired to produce only naphtha cuts.

The second hydrocracking step b″) is carried out in a hydrocracking reaction section, using at least one fixed bed comprising n catalyst layers, each of which n is an integer greater than 1, and which includes at least one hydrocracking catalyst, so that the separation step obtaining a hydrocracked effluent which is sent to c), said hydrocracking reaction section being fed with at least a cut containing compounds having a boiling point greater than 175° C. obtained from step d) and a gas stream containing hydrogen, said hydrocracking reaction section being The section is used at an average temperature between 250 and 450° C., a hydrogen partial pressure between 1.5 and 20.0 MPa abs. and an hourly space velocity between 0.1 and 10.0 h ⁻¹ Preferred operating conditions and catalysts used in the second hydrocracking stage are those described for the first hydrocracking stage The operating conditions and catalysts used for the two hydrocracking stages may be the same or different.

The second hydrocracking stage is advantageously carried out in a hydrocracking reaction section comprising at least one, preferably 1 to 5 fixed bed reactors comprising n catalyst layers, n being at least 1, preferably 1 to 10 , preferably an integer from 2 to 5, wherein the layer(s) each contain at least one, preferably no more than 10 hydrocracking catalysts.

These operating conditions used in the hydrocracking step(s) generally have a boiling point of less than 175°C, preferably less than 160°C, preferably less than 150°C and contain greater than 15% by weight, even more preferably 20 to 95% by weight % conversion per pass to a product having at least 80% by volume of the compound. When the process is carried out in two hydrocracking stages, the conversion per pass in the second stage is kept reasonable to maximize the selectivity for compounds on the naphtha cut (boiling point below 175°C, especially between 80 and 175°C). do. Conversion per pass is limited by using a high recycle rate on the second hydrocracking stage loop. This ratio is defined as the ratio of the feed flow rate of step b″) to the feedstock flow rate of step a); preferably this ratio is between 0.2 and 4, preferably between 0.5 and 2.5.

Thus, the hydrocracking step(s) does not necessarily make it possible to convert all compounds with a boiling point above 175°C (diesel cut) to compounds with a boiling point below 175°C (naphtha cut). Thus, after fractionation step d), a greater or less significant proportion of compounds with a boiling point above 175° C. may remain. To increase conversion, at least a portion of this unconverted cut can be recycled as described in step b′) below, or sent to the second hydrocracking stage b″). Another portion can be purged. Depending on the operating conditions of the process, it may be from 0 to 10%, preferably from 0.5% to 5%, by weight of the cut comprising a compound having a boiling point greater than 175° C. relative to the incoming feedstock to be purged.

According to the present invention, the hydrocracking step(s) operates in the presence of at least one hydrocracking catalyst.

The hydrocracking catalyst(s) used in the hydrocracking step(s) are conventional hydrocracking catalysts known to those skilled in the art, of the bifunctional type combining acid action and hydrodehydrogenation action and optionally of at least one binder matrix. The acid function is provided by supports having a large surface area (typically 150 to 800 m/g) with surface acidity, such as halogenated (especially chlorinated or fluorinated) aluminas, combinations of boron and aluminum oxides, amorphous silica-aluminas and zeolites . The hydrodehydrogenation function is provided by at least one metal from group VIB and/or at least one metal from group VIII of the periodic table.

Preferably, the hydrocracking catalyst(s) is a hydro-dehydrogenation catalyst comprising at least one metal from group VIII selected from iron, cobalt, nickel, ruthenium, rhodium, palladium and platinum, preferably cobalt and nickel. Include features. Preferably, the catalyst(s) also comprises at least one metal from group VIB selected from chromium, molybdenum and tungsten, alone or as a mixture, preferably from molybdenum and tungsten. A hydrogen-dehydrogenation function of the NiMo, NiMoW or NiW type is preferred.

Preferably, the content of metals from group VIII in the hydrocracking catalyst(s) is advantageously between 0.5% and 15% by weight, preferably between 1% and 10% by weight, the percentage being relative to the total weight of the catalyst. It is expressed as a weight percentage of oxide. When the metal is cobalt or nickel, the metal content is indicated by CoO and NiO, respectively.

Preferably, the content of metals from group VIB in the hydrocracking catalyst(s) is advantageously between 5% and 35% by weight, preferably between 10% and 30% by weight, the percentage being in relation to the total weight of the catalyst It is expressed as a weight percentage of oxide. When the metal is molybdenum or tungsten, the metal content is indicated by MoO ₃ and WO ₃ , respectively.

The hydrocracking catalyst(s) is also optionally deposited on the catalyst and contains at least one promoter element selected from the group formed by phosphorus, boron and silicon, optionally at least one element from group VIIA (preferably chlorine and fluorine), optionally at least one element from group VIIB (preferably manganese), and optionally at least one element from group VB (preferably niobium).

Preferably, the hydrocracking catalyst(s) is selected from alumina, silica, silica-alumina, aluminate, alumina-boron oxide, magnesia, silica-magnesia, zirconia, titanium oxide or clay, alone or as a mixture, preferably alumina or at least one amorphous or poorly crystallized porous mineral matrix of an oxide type selected from silica-alumina, alone or as a mixture.

Preferably, the silica-alumina contains more than 50% by weight of alumina, preferably more than 60% by weight of alumina.

Preferably, the hydrocracking catalyst(s) is a Y zeolite, preferably a zeolite selected from USY zeolites alone or beta, ZSM-12, ZSM-2, ZSM-22, ZSM-23, SAPO-11, ZSM- 48 or ZBM-30 zeolites, alone or as mixtures, in combination with other zeolites. Preferably, the zeolite is USY zeolite alone.

If the catalyst comprises zeolites, the content of zeolites in the hydrocracking catalyst(s) is advantageously between 0.1% and 80% by weight, preferably between 3% and 70% by weight, the percentage being relative to the total weight of the catalyst. Expressed as a percentage of zeolite.

Preferred catalysts comprise at least one metal from group VIB and optionally at least one non-noble metal from group VIII, at least one promoter element, and preferably phosphorus, at least one Y zeolite and at least one alumina binder; , preferably composed of them.

Even more preferred catalysts include, preferably consist of, nickel, molybdenum, phosphorus, USY zeolites, and optionally also beta zeolites, and alumina.

Other preferred catalysts include, preferably consist of, nickel, tungsten, alumina and silica-alumina.

Other preferred catalysts include, preferably consist of, nickel, tungsten, USY zeolite, alumina and silica-alumina.

The hydrocracking catalyst is for example in the form of an extrudate.

In one variant, the hydrocracking catalyst used in step b″) comprises a hydrogenation-dehydrogenation function comprising at least one noble metal from group VIII selected from palladium and platinum, alone or as a mixture. The noble metal content of is advantageously between 0.01% and 5% by weight, preferably between 0.05% and 3% by weight, the percentage expressed as weight percentage of oxide (PtO or PdO) relative to the total weight of the catalyst.

According to another aspect of the present invention, the hydrocracking catalyst as described above also comprises at least one organic compound containing oxygen and/or nitrogen and/or sulfur. Such catalysts are often denoted by the term "added catalyst". In general, the organic compound has one or more functional groups selected from carboxyl, alcohol, thiol, thioether, sulfone, sulfoxide, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea, and amide functional group. compounds containing chemical functional groups or compounds containing furan rings or other sugars.

The preparation of catalysts for steps a), b), b') or b") is known and generally involves adding a Group VIII metal and a Group VIB metal, if present, and optionally phosphorus and/or boron onto a support. Impregnated, followed by drying, followed by optional calcination. In the case of added catalysts, preparation generally takes place by introducing organic compounds and then simple drying without calcination. In this specification, the term "calcination" is It means heat treatment under air or oxygen-containing gas at a temperature above 200 ° C. Before use in a process step, the catalyst is usually subjected to sulfiding to form active species. The catalyst of step a) is also in reduced form. can also be a catalyst used as a catalyst, and thus its preparation involves a reduction step.

The gaseous stream comprising hydrogen which is fed to the reaction section of steps a), b), b′) or b″) may consist of a feed of hydrogen and/or in particular recycled hydrogen obtained from separation step c). Preferably, a further gas stream comprising hydrogen is advantageously introduced into the inlet of each reactor, in particular operated in series, and/or into the inlet of each catalyst bed from the second catalyst bed of the reaction section. The additional gas stream is also referred to as the cooling stream, which allows to control the temperature in the reactor where the reactions involved are generally highly exothermic.

Optionally, each of steps a), b), b') or b") may use a heating section located upstream of the reaction section and in which the inlet effluent is heated to reach a suitable temperature. Thus, an optional heating section may preferably include one or more exchangers allowing heat exchange between the hydrotreated effluent and the hydrocracked effluent, and/or a preheating oven.

However, carrying out step a) at a relatively high average temperature with an increasing profile optionally eliminates the need for a heating device or at least the thermal requirement between the hydrogenation catalyst section of step a) and the hydrotreating catalyst section of step b). makes it possible to reduce

Separation step c)

According to the invention, the treatment process advantageously comprises a separation step c), which is the hydrotreated effluent obtained from step b) or the hydrocracked effluent obtained from any of steps b') and b"). , and in at least one wash/separation section receiving at least an aqueous solution to obtain at least one gaseous effluent, an aqueous effluent and a hydrocarbon-based effluent.

The gaseous effluent obtained at the end of step c) advantageously comprises hydrogen, preferably at least 80% by volume, preferably at least 85% by volume of hydrogen. Advantageously, the gaseous effluent can be at least partially recycled to the hydrogenation step a) and/or the hydrotreating step b) and/or the hydrocracking step b′) and/or the hydrocracking step b″), the recirculation system possibly contains a purification section.

The aqueous effluent obtained at the end of step c) advantageously comprises an ammonium salt and/or hydrochloric acid.

In particular, this separation step c) results in the release of chloride ions by the hydrogenation of the chlorinated compound, especially in the form of HCl during steps a) and b) followed by dissolution in water, and nitrogen-containing compounds, in particular in the form of NH3 during step b). making it possible to remove the ammonium chloride salt formed by the reaction between ammonium ions produced by hydrogenation of the compound and/or provided by injection of an amine followed by dissolution in water, owing to the precipitation of the ammonium chloride salt, in particular in the conveying line and/or sections of the process of the present invention and/or delivery lines to the steam cracker. In addition, it is also possible to remove hydrochloric acid formed by the reaction of hydrogen ions and chloride ions.

As a function of the content of chlorinated compounds in the initial feedstock to be treated, the stream containing amines, for example monoethanolamine, diethanolamine and/or monodiethanolamine, is selected upstream of hydrogenation step a) and/or hydrogenation step a). ) and the hydrotreating step b) and/or between the hydrocracking step b′) and the separation step c), preferably upstream of the hydrogenation step a), such that a sufficient amount of ammonium ions are formed during the hydrotreating step. By ensuring that it is combined with, it is possible to limit the formation of hydrochloric acid and thus limit corrosion downstream of the separation section.

Advantageously, the separation step c) at least partially dissolves the ammonium chloride salt and/or hydrochloric acid in a washing/separation section to improve the removal of chlorinated impurities and reduce the risk of clogging caused by the accumulation of ammonium chloride salts. into the hydrotreated effluent obtained from step b) or into the hydrocracked effluent obtained from optional steps b') and b") upstream of the injection of an aqueous solution, preferably water.

Separation step c) is advantageously carried out at a temperature of 50 to 450 °C, preferably 100 to 440 °C, preferably 200 to 420 °C. It is important to carry out the step in this temperature range (and therefore not to cool the hydroconverted effluent too much) at the risk of blockage in the line due to precipitation of the ammonium chloride salt. Advantageously, the separation step c) is carried out at a pressure close to that used in steps a) and/or b), preferably between 1.0 and 20.0 MPa, to facilitate recycling of the hydrogen.

The washing/separation section of step c) may be carried out at least partly in common or separate washing and separation equipment (separation vessels, pumps, heat exchangers, washing columns, etc. capable of operating at various pressures and temperatures). ) is well known.

In one optional embodiment of the present invention, the separation step c) comprises the injection of an aqueous solution into the hydrotreated effluent obtained from step b), then the washing/separation section is advantageously charged with at least one ammonium salt. It includes separate phases to obtain an aqueous effluent, a scrubbed liquid hydrocarbon-based effluent and a partially scrubbed gaseous effluent. The aqueous effluent charged with ammonium salt and the washed liquid hydrocarbon-based effluent may subsequently be separated in a decanting vessel to obtain the hydrocarbon-based effluent and the aqueous effluent. The partially washed gaseous effluent may be introduced in parallel into a washing column which is circulated countercurrently to the aqueous stream, preferably of the same nature as the aqueous solution injected into the hydrotreated effluent, which is partially washed. It is possible to at least partially, preferably entirely remove the hydrochloric acid contained in the gaseous effluent which has been treated, to obtain said gaseous effluent which preferably essentially comprises hydrogen, and an acidic aqueous stream. The aqueous effluent obtained from the decanting vessel may optionally be mixed with the acidic aqueous stream, optionally as a mixture with the acidic aqueous stream, in a water recirculation circuit, the aqueous solution upstream of the washing/separation section. and/or to feed step c) of separating into said aqueous stream of a wash column. The water recirculation circuit may include a supply of water and/or a supply of a basic solution and/or a purge to remove dissolved salts.

In another optional embodiment of the present invention, the separation step c) advantageously comprises the hydrogenation step a) and/or the hydrotreating step b) and/or the optional hydrocracking step b′) to facilitate recycling of the hydrogen. It may include a "high pressure" wash/separation section operating at a pressure close to that of This optional “high pressure” section of step c) is dissolved at high pressure and is “low pressure” to obtain a hydrocarbon-based liquid fraction free of a portion of gas intended to be directly processed in a steam cracking process or optionally sent to fractionation step d). It can be done in sections.

The gas fraction(s) obtained from separation step c) is at least one hydrogen-rich gas which can be recycled upstream of step a) and/or b) and/or b') and/or b") and/or For the purpose of recovering light hydrocarbons, in particular ethane, propane and butanes, which may be subjected to further purification(s) and separation(s), which are separately in one or more furnaces of steam cracking step e) to increase the overall yield of olefins. or as a mixture.

The hydrocarbonaceous effluent obtained from separation step c) is partly or wholly passed directly to the inlet of the steam cracking unit or to an optional fractionation step d). Preferably, the hydrocarbon-based liquid effluent is partially or wholly, preferably entirely, sent to the fractionation step d).

fractionation step d) (optional)

The process according to the invention may comprise fractionating all or part, preferably all, of the hydrocarbon-based effluent obtained from step c) to obtain at least one gaseous stream and at least two liquid hydrocarbon-based streams. wherein the two liquid hydrocarbon-based streams are at least one naphtha cut comprising compounds having a boiling point below 175°C, particularly between 80 and 175°C, and one hydrocarbon cut comprising compounds having a boiling point above 175°C. am.

Step d) makes it possible in particular to remove gases dissolved in the hydrocarbon-based liquid effluent, for example ammonia, hydrogen sulphide and light hydrocarbons containing 1 to 4 carbon atoms.

Optional fractionation step d) is advantageously carried out at a pressure of less than or equal to 1.0 MPa abs, preferably from 0.1 to 1.0 MPa abs.

According to one embodiment, step d) may advantageously be carried out in a section comprising at least one stripping column equipped with a reflux circuit comprising a reflux vessel. The stripping column is fed with the hydrocarbon-based liquid effluent and vapor stream obtained from step c). The hydrocarbon-based liquid effluent obtained from step c) may optionally be heated before entering the stripping column. Thus, the lightest compounds are incorporated at the top of the column and into the reflux circuit comprising a reflux vessel, where gas/liquid separation takes place. The gas phase comprising light hydrocarbons is withdrawn from the reflux vessel as a gas stream. Naphtha cuts comprising compounds with boiling points below 175° C. are advantageously withdrawn from the reflux vessel. The hydrocarbon cut comprising compounds with a boiling point above 175° C. is advantageously withdrawn at the bottom of the stripping column.

According to other embodiments, said fractionation step d) may comprise a distillation column or only a distillation column following the stripping column.

The naphtha cut comprising compounds boiling below 175°C and the cut comprising compounds boiling above 175°C optionally mixed may be sent wholly or partly to a steam cracking unit, at the outlet of the steam cracking unit olefin may be (re)formed to participate in polymer formation. Preferably, only a portion of the cut is sent to the steam cracking unit; At least a portion of the remaining portion is optionally recycled to at least one of the stages of the process and/or sent to a fuel storage unit, for example a naphtha storage unit obtained from conventional petroleum feedstock, a diesel storage unit or a kerosene storage unit.

According to a preferred embodiment, the naphtha cut comprising compounds with a boiling point below 175°C is sent in whole or in part to a steam cracking unit, while the cut comprising compounds with a boiling point above 175°C is sent to step a) and/or or recycled to b) and/or b′) and/or sent to a fuel storage unit.

In one particular embodiment, the optional fractionation step d) comprises, in addition to the gas stream, a naphtha cut comprising compounds having a boiling point below 175°C, preferably between 80 and 175°C, and between above 175°C and below 385°C. It is also possible to obtain a middle distillate cut comprising compounds having a boiling point, and a hydrocarbon cut comprising compounds having a boiling point above 385° C., known as a heavy hydrocarbon cut. The naphtha cut may be sent in whole or in part to a steam cracking unit and/or to a storage unit for naphtha obtained from conventional petroleum-based feedstock; can also be recycled; The middle-distillate cut may also be sent, in whole or in part, to a steam cracking unit, or to a storage unit for diesel obtained from conventional petroleum-based feedstock, or recycled; The heavy cuts can be sent to the steam cracking unit at least in part or recycled to that part.

In another particular embodiment, the optional fractionation step e) comprises, in addition to the gas stream, a naphtha cut comprising compounds having a boiling point below 175°C, preferably between 80 and 175°C, and a boiling point above 175°C and below 280°C. A kerosene cut comprising a compound having a boiling point of greater than 280°C to less than 385°C, a diesel cut comprising a compound having a boiling point, and a hydrocarbon cut comprising a compound having a boiling point of 385°C or higher known as a heavy hydrocarbon cut can be obtained. can make it Naphtha cuts may be sent wholly or partially to a steam cracking unit and/or to a naphtha pool obtained from conventional petroleum-based feedstocks; It may also be sent to the recycling step g); The kerosene or diesel cuts may also be sent wholly or partly respectively to a steam cracking unit, or to a kerosene or diesel pool obtained from conventional petroleum-based feedstocks, or to recycle step f); The heavy cuts may at least partly be sent to the steam cracking unit or to the recycling step f).

In another specific embodiment, the naphtha cut comprising compounds having a boiling point below 175°C obtained from step d) has a heavy naphtha cut comprising compounds having a boiling point between 80 and 175°C and a boiling point below 80°C. fractionated into light naphtha cuts containing compounds, and at least a portion of the heavy naphtha cuts are sent to an aromatic complex comprising at least one naphtha reforming stage to produce aromatic compounds. According to this embodiment, at least part of the light naphtha cut is sent to the steam cracking step e) described below.

The gaseous fraction(s) obtained from fractionation step d) may be subjected to further purification(s) and separation(s) for the purpose of recovering at least light hydrocarbons, in particular ethane, propane and butanes, which increases the overall yield of olefins. They may advantageously be sent individually or as a mixture to one of the furnaces of steam cracking step E) for processing.

Recycling of cuts containing compounds with a boiling point greater than 175 °C

At least one fraction of the cut comprising compounds having a boiling point greater than 175° C. obtained from the fractionation step d) is recovered, in which at least one of the reaction steps of the process according to the invention, in particular the hydrogenation step a) and/or hydrogen It is possible to constitute a recycle stream which is sent upstream or directly to the treatment stage b) and/or the hydrocracking stage b'). Optionally, a fraction of the recycle stream may be sent to optional step a0).

The recycle stream is fed in a single injection to reaction stages a) and/or b) and/or b'), or in several fractions to feed reaction stages a) and/or b) and/or b') in several injections. , ie into different catalytic layers.

Advantageously, the amount of the recycle stream of the cut comprising compounds with a boiling point greater than 175° C. is such that the weight ratio between the recycle stream and the feedstock comprising plastic pyrolysis oil, i.e. the feedstock to be treated which is fed to the overall process, is 10 or less; It is adjusted so that it is preferably 5 or less, and preferentially 0.001 or more, preferably 0.01 or more, preferably 0.1 or more. Very preferably, the amount of the recycle stream is adjusted such that the weight ratio between the recycle stream and the feedstock comprising plastic pyrolysis oil is between 0.2 and 5.

According to one preferred variant, at least a fraction of the cut comprising compounds having a boiling point greater than 175° C. obtained from fractionation step d), if present, is sent to a hydrocracking step b′). By recycling a part of the cut comprising compounds with a boiling point above 175°C into at least one of the reaction stages of the process according to the invention, in particular the hydrocracking stage b'), advantageously the yield of naphtha cuts with a boiling point below 175°C can increase Recirculation also allows for dilution of impurities and moreover allows for temperature control in reaction step(s) where the reactions involved can be highly exothermic.

According to another preferred variant, at least a fraction, if present, of the cut comprising compounds having a boiling point greater than 175° C. obtained from fractionation step d) is sent to a second hydrocracking step b″).

A purge may be installed in the recirculation of cuts containing compounds with a boiling point greater than 175 ° C. Depending on the operating conditions of the process, the purge may be from 0 to 10%, preferably from 0.5% to 5%, by weight of the cut comprising a compound having a boiling point greater than 175° C. relative to the incoming feedstock.

Recycle of the hydrocarbon-based effluent obtained from step c) and/or the naphtha cut having a boiling point below 175° C. obtained from step d)

The fraction of the hydrocarbon-based effluent obtained from separation step c) or the fraction of naphtha cuts having a boiling point below 175° C. obtained from optional fractionation step d) can be recovered to constitute a recycle stream, which is the process according to the present invention. is sent upstream or directly to at least one of the reaction stages of, in particular the hydrogenation stage a) and/or the hydrotreating stage b). Optionally, a fraction of the recycle stream may be sent to an optional pre-treatment step a0).

Preferably, at least a fraction of the hydrocarbon-based effluent obtained from the separation step c) or the naphtha cut obtained from the optional fractionation step d) having a boiling point below 175° C. is fed to the hydrotreating step b).

Advantageously, the amount of the recycle stream, ie the fraction of recycled product obtained, is such that the weight ratio between the recycle stream and the feedstock comprising plastic pyrolysis oil, ie the feedstock to be treated which is fed to the overall process, is at most 10, preferably is adjusted to be 5 or less, and preferentially 0.001 or more, preferably 0.01 or more, preferably 0.1 or more. Very preferably, the amount of the recycle stream is adjusted such that the weight ratio between the recycle stream and the feedstock comprising plastic pyrolysis oil is between 0.2 and 5.

Advantageously, in start-up phases of the process, a hydrocarbon cut outside the process may be used as a recycle stream. A person skilled in the art will then know how to select the hydrocarbon cut.

Recycling a part of the product obtained into or upstream of at least one of the reaction steps of the process according to the invention advantageously firstly makes it possible to dilute impurities and secondly a reaction step in which the reactions involved can be highly exothermic. Allows temperature control in (s).

Thus, the hydrocarbon-based effluent or hydrocarbon-based stream(s) obtained by the treatment of plastic pyrolysis oil according to the process of the present invention has a composition compatible with the specifications of the feedstock entering the steam cracking unit. In particular, the composition of the hydrocarbon-based effluent or hydrocarbon-based stream(s) is preferably:

- the total content of metal elements is less than or equal to 5.0 ppm by weight, preferably less than or equal to 2.0 ppm by weight, preferably less than or equal to 1.0 ppm by weight, preferably less than or equal to 0.5 ppm by weight;

The content of silicon element (Si) is 1.0 ppm by weight or less, preferably 0.6 ppm by weight or less,

The content of iron element (Fe) is 100 ppb or less by weight,

- a sulfur content of less than or equal to 500 ppm by weight, preferably less than or equal to 200 ppm by weight,

- the nitrogen content is less than or equal to 100 ppm by weight, preferably less than or equal to 50 ppm by weight, preferably less than or equal to 5 ppm by weight,

- The asphaltene content is less than 5.0 ppm by weight,

- the total content of elemental chlorine is less than or equal to 10 ppm by weight, preferably less than 1.0 ppm by weight,

- The content of olefin compounds (monolephins and diolefins) is 5.0% by weight or less, preferably 2.0% by weight or less, preferably 0.1% by weight or less.

The content is given as a relative weight concentration, weight percentage (%), weight parts per million (pppm) or weight parts per billion (ppb), relative to the total weight of the stream under consideration.

Thus, the process according to the invention makes it possible to treat plastic pyrolysis oil to obtain an effluent which can be wholly or partially injected into a steam cracking unit.

Steam cracking step e) (optional)

The hydrocarbon-based effluent obtained from separation step c), or at least one of the two liquid hydrocarbon-based streams obtained from optional step d) may be sent wholly or partly to steam cracking step e).

Advantageously, the gas fraction(s) obtained from separation step c) and/or fractionation step d) and containing ethane, propane and butanes may also be entirely or partly sent to steam cracking step e).

Steam cracking step e) is advantageously carried out in at least one pyrolysis furnace at a temperature of 700 to 900° C., preferably 750 to 850° C. and a relative pressure of 0.05 to 0.3 MPa. The residence time of the hydrocarbon-based compound is generally 1.0 second (indicated by s) or less, preferably 0.1 to 0.5 s. Steam is advantageously introduced upstream of the optional steam cracking step e) and after separation (or fractionation). Advantageously, the amount of water introduced in vapor form is between 0.3 and 3.0 kg of water per kg of hydrocarbon-based compound entering step e). Optional step e) is preferably carried out in a plurality of pyrolysis furnaces in parallel in order to adapt the operating conditions to the various stream feed steps e) and in particular to manage the tube decoking time obtained from step d) . The furnace includes one or more tubes arranged in parallel. A furnace can also refer to a group of furnaces operating in parallel. For example, a furnace may be dedicated to cracking naphtha cuts containing compounds with a boiling point below 175 °C.

Effluents from various steam cracking furnaces are generally recombined prior to separation to form the effluent. Steam cracking step e) is understood to include not only a steam cracking furnace but also sub-steps related to steam cracking well known to those skilled in the art. This sub-stage may include recycling into heat exchangers, columns and catalytic reactors and furnaces, among others. The column generally produces an effluent for the purpose of recovering at least one light fraction comprising hydrogen and compounds containing 2 to 5 carbon atoms, and a fraction comprising pyrolysis gasoline, and optionally comprising pyrolysis oil. makes it possible to differentiate. The column makes it possible to separate the various components of the fractionated light fraction to recover at least one ethylene-rich cut (C2 cut) and propylene-rich cut (C3 cut) and optionally butene-rich cut (C4 cut). Catalytic reactors make it possible in particular to carry out the hydrogenation of C2, C3 or even C4 cut and pyrolysis gasoline. Saturated compounds, especially those containing 2 to 4 carbon atoms, are advantageously recycled to the steam cracking furnace to increase the overall yield of olefins.

This steam cracking step e) comprises olefins comprising 2, 3 and/or 4 carbon atoms (i.e. C2, C3 and/or C4 olefins) in a satisfactory content, by weight of the steam cracking effluent considered, of 2 , in particular at least 30%, in particular at least 40%, or even at least 50% by weight of the total olefins comprising 3 and/or 4 carbon atoms. The C2, C3 and C4 olefins may then advantageously be used as polyolefin monomers.

According to one preferred embodiment of the present invention, the process of treating a feedstock comprising plastics pyrolysis oil comprises, preferably consists of, the following sequence of steps, preferably in a given sequence:

- hydrogenation step a), hydrotreating step b), separation step c), or

- hydrogenation step a), hydrotreating step b), separation step c) and fractionation step d), or

- hydrogenation step a), hydrotreating step b), separation step c), fractionation step d) and recycling to step a) and/or b) of the cut comprising compounds having a boiling point below 175 °C;

- hydrogenation step a), hydrotreating step b), hydrocracking step b'), separation step c), or

- hydrogenation step a), hydrotreating step b), hydrocracking step b'), separation step c) and fractionation step d), or

- hydrogenation step a), hydrotreating step b), hydrocracking step b'), separation step c), fractionation step d) and recycling of the cut comprising compounds with a boiling point above 175 ° C to the hydrocracking step b'), or

- hydrogenation step a), hydrotreating step b), hydrocracking step b′), separation step c), fractionation step d) and recycling to step a) or b) of the cut comprising compounds having a boiling point below 175 ° C. , or

- hydrogenation step a), hydrotreating step b), hydrocracking step b'), separation step c), fractionation step d), recycling to hydrocracking step b') of the cut comprising compounds having a boiling point above 175 °C and recycling to step a) or b) of a cut comprising a compound having a boiling point of less than or equal to 175°C, or

- hydrogenation step a), hydrotreating step b), hydrocracking step b'), separation step c), fractionation step d) and recycling to the hydrocracking step b”) of the cut comprising compounds with a boiling point greater than 175 ° C, or

- hydrogenation step a), hydrotreating step b), hydrocracking step b'), separation step c), fractionation step d), recycling to hydrocracking step b") of the cut comprising compounds having a boiling point above 175 ° C. and recycling to step a) or b) of a cut comprising a compound having a boiling point of less than or equal to 175°C, or

- hydrogenation step a), hydrotreating step b), separation step c), fractionation step d) and hydrocracking step b′), or

- recycling of the effluents from hydrogenation step a), hydrotreating step b), separation step c), fractionation step d) and hydrocracking step b') and step b') into step c), or

- recycling into step c) of the effluents from hydrogenation step a), hydrotreating step b), separation step c), fractionation step d) and hydrocracking step b') and step b'), and boiling point of less than or equal to 175 ° C. recycling to step a) or b) of the cut containing the compound with

All embodiments may also include, and preferably consist of, a pretreatment step a0).

All embodiments may also include, and preferably consist of, a steam cracking step g).

Analysis method used

The analytical methods and/or standards used to determine the properties of the various streams, particularly the feedstocks and effluents to be treated, are known to those skilled in the art. These are specifically listed below in an informative way. Other well-known equivalence methods may also be used, in particular the equivalence IP, EN or ISO methods:

Information about elements referenced in FIGS. 1 to 2 allows a better understanding of the present invention, which is not limited to the specific embodiments shown in FIGS. 1 to 2 . The various embodiments presented can be used alone or in combination with each other, without any limitation to the combination.
Figure 1 shows a scheme of a particular embodiment of the process of the present invention, including:
- in the presence of a hydrogen-rich gas (2) and optionally an amine supplied by stream (3), carried out in at least one fixed bed reactor comprising at least one hydrogenation catalyst, to obtain an effluent (4) , hydrogenation step a) of a hydrocarbon-based feedstock obtained from pyrolysis of plastic (1);
- of the effluent (4) obtained from step a) in the presence of hydrogen (5), carried out in at least one fixed bed reactor comprising at least one hydrotreating catalyst, to obtain a hydrotreated effluent (6) Hydrotreating step b);
- the effluent obtained from step b), optionally in the presence of hydrogen (7), carried out in at least one fixed bed reactor comprising at least one hydrocracking catalyst, to obtain a hydrotreated effluent (8) ( 6) the hydrogen cracking step b');
- in the presence of an aqueous washing solution (9), which makes it possible to obtain at least one fraction (10) comprising hydrogen, an aqueous fraction (11) containing dissolved salts, and a hydrocarbon-based liquid fraction (12) Separation step c) of the effluent (8) carried out;
- optionally, the hydrocarbon-based liquid fraction (12) is fractionated to form one or more gaseous fractions (13), a cut (14) comprising compounds with a boiling point below 175 ° C (naphtha cut) and a compound with a boiling point above 175 ° C. A fractionation step d) which makes it possible to obtain cut (15) (diesel cut).
As a result of step d), a portion of the cut 14 containing compounds with boiling points below 175° C. is sent to a steam cracking process (not shown). Another part of the cut 14 is fed to the hydrogenation step a) (fraction 14a) and to the hydrotreating step b) (fraction 14b). Part of the cut (15) comprising compounds having a boiling point above 175 ° C obtained from step d) is fed to the hydrocracking step b') (fraction (15a)), the other part (15b) constitutes a purge .
FIG. 2 shows the way of another particular embodiment of the process of the present invention based on the way of FIG. 1 . This scheme comprises in particular a second hydrocracking stage b″), wherein the cut 15 comprising compounds obtained from step d) having a boiling point greater than 175° C. is a second hydrocracking stage b″) ( fraction 15a), which is carried out in one or more fixed bed reactors containing one or more hydrocracking catalysts and supplied with hydrogen (16). The second hydrocracked effluent (17) is recycled to the separation step c). Another part of the cut 15 constitutes the purge 15b.
Instead of injecting the amine stream (3) into the inlet of the hydrogenation step a), depending on the nature of the feedstock, into the inlet of the hydrotreating step b), into the inlet of the hydrocracking step b′), into the inlet of the separation step c) It is possible to inject into the inlet or otherwise not inject.
In order to allow a good understanding of the present invention, only the main stages together with the main stream are shown in FIGS. 1 and 2 . Although not shown, it can be clearly seen that all equipment necessary for functioning (vessel, pump, exchanger, furnace, column, etc.) is present. Also, as noted above, it is understood that a hydrogen-rich gas stream (feed or recycle) may be injected into the inlet of each reactor or catalyst bed or between two reactors or two catalyst beds. Means well known to those skilled in the art for hydrogen purification and recycling can also be used.

yes

Example 1 (according to the present invention)

The feedstock treated in the process is a plastic pyrolysis oil having the properties shown in Table 2 (i.e. comprising 100% by weight of the plastic pyrolysis oil).

The feedstock (1) is subjected to a hydrogenation step a) carried out in a fixed bed reactor and in the presence of hydrogen (2) and a hydrogenation catalyst of the type NiMo on alumina, under the conditions shown in Table 3.

The conditions shown in Table 3 are conditions at the start of the cycle, in which the average temperature (WABT) is increased by 1°C per month to compensate for catalyst deactivation.

In the product of hydrogenation step a), the observed conversion (= (initial concentration - final concentration)/initial concentration) is shown in Table 4.

The effluent (4) obtained from the hydrogenation step a) is directly subjected without separation to the hydrotreating step b) carried out in a fixed bed in the presence of hydrogen (5) and a hydrotreating catalyst of the type NiMo on alumina under the conditions given in table 5.

The conditions shown in Table 5 are conditions at the start of the cycle, in which the average temperature (WABT) is increased by 1°C per month to compensate for catalyst deactivation.

The effluent (6) obtained from hydrotreating step b) is subjected to a separation step c): a water stream is injected into the effluent obtained from hydrotreating step b); The mixture is then processed in an acid gas wash column and separation vessel to obtain a gas fraction and a liquid effluent. The yields for the various fractions obtained after separation are shown in Table 6 (the yields correspond to the ratio of the mass amounts of the various products obtained to the mass of the feedstock upstream of step a), expressed as percentages and % m/m indicated by ).

All or part of the obtained liquid fraction can then be upgraded in a steam cracking step for the purpose of forming polymerizable olefins for the purpose of forming recycled plastics.

The process carried out according to the invention reduces the catalyst deactivation during the hydrogenation step a) and during the hydrotreating step b) compared to the catalyst deactivation observed according to the prior art.

Example 2 (not according to the invention)

In this example according to the prior art and not according to the present invention, the feedstock to be treated is the same as that described in Example 1 (see Table 2).

The feedstock is subjected to a selective hydrogenation step a) carried out in a fixed bed reactor and in the presence of hydrogen and a selective hydrogenation catalyst of the NiMo on alumina type under the conditions shown in Table 7.

The conditions shown in Table 7 are those at the start of the cycle, in which the average temperature (WABT) is increased by 4°C per month to compensate for catalyst deactivation.

In the product of the selective hydrogenation step a), the observed conversions (= (initial concentration - final concentration)/initial concentration) are shown in Table 8.

The effluent obtained from the selective hydrogenation step a) is subjected to a hydrotreating step b) carried out without separation under the conditions given in Table 9 in a fixed bed in the presence of hydrogen, a hydrocarbon-based recycle stream and a hydrotreating catalyst of the type NiMo on alumina. applied directly.

The conditions shown in Table 9 are those at the start of the cycle, in which the average temperature (WABT) was increased by 2°C per month to compensate for catalyst deactivation.

The effluent obtained from hydrotreating step b) is subjected to a separation step c): a water stream is injected into the effluent obtained from hydrotreating step b); The mixture is then processed in an acid gas wash column and separation vessel to obtain a gas fraction and a liquid effluent. The yields for the various fractions obtained after separation are shown in Table 10 (the yields correspond to the ratio of the mass amounts of the various products obtained to the mass of the feedstock upstream of step a), expressed as percentages and % m/m indicated by ).

Processes carried out according to the prior art and not according to the present invention are observed during the selective hydrogenation step a) and during the hydrotreating step b), in the process carried out according to the present invention during the hydrogenation step a) and during the hydrotreating step b). It results in greater catalyst deactivation than catalyst deactivation.

Claims (18)

A method for processing a feedstock comprising plastic pyrolysis oil,
a) hydrogenation carried out in a hydrogenation reaction section to obtain a hydrogenated effluent using at least one fixed bed reactor comprising n catalyst beds, where n is an integer greater than or equal to 1, each comprising at least one hydrogenation catalyst. Step, said hydrogenation reaction section is fed with at least said feedstock and a hydrogen containing gas stream, said hydrogenation reaction section having an average temperature between 140 and 400° C., 1.0 and 10.0 MPa abs. said hydrogenation step, wherein the temperature at the outlet of the reaction section of step a) is at least 15° C. higher than the temperature at ^the inlet of the reaction section of step a),
b) using at least one fixed bed reactor comprising n catalyst beds, where n is an integer greater than 1, each comprising at least one hydrotreatment catalyst, carried out in a hydrotreatment reaction section to produce a hydrotreated effluent. a hydrotreating step to obtain, wherein the hydrotreating reaction section is fed with at least the hydrogenated effluent obtained from step a) and the hydrogen containing gas stream, the hydrotreating reaction section having an average temperature between 250 and 430° C., 1.0 and 10.0 MPa abs. said hydrotreating step, wherein the average temperature of the reaction section of step ^b ) is higher than the average temperature of the hydrogenation reaction section of step a);
b') optionally carried out in a hydrocracking reaction section, using at least one fixed bed comprising n catalyst beds, each containing at least one hydrocracking catalyst, wherein n is an integer greater than 1, wherein the separation step c) wherein the hydrocracking reaction section contains at least the hydrotreated effluent obtained from step b) and/or the boiling point greater than 175° C. obtained from step d). and a gas stream containing hydrogen and a cut containing a compound having an average temperature between 250 and 450° C., 1.5 and 20.0 MPa abs. the hydrogen cracking step, wherein the hydrogen cracking step is used at a hydrogen partial pressure between 0.1 and 10.0 h ^-1 hourly space velocity;
c) said hydrotreated effluent obtained from step b) or said hydrocracked effluent obtained from step b′) and an aqueous solution carried out at a temperature between 50 and 370° C., wherein at least one gas outlet a separation step to obtain water, an aqueous effluent and a hydrocarbon-based effluent;
d) optionally fractionating all or part of said hydrocarbonaceous effluent obtained from step c) to at least one gaseous effluent and at least one cut comprising compounds having a boiling point of less than or equal to 175°C and a boiling point greater than 175°C. A fractionation step to obtain one hydrocarbon-based cut comprising a compound having The method of claim 1 comprising step d). 3. The method according to claim 1 or 2, comprising step b'). 4. The process according to any one of claims 1 to 3, wherein the amount of the hydrogen-containing gas stream fed to the reaction section of step a) is such that the hydrogen coverage is between 50 and 1000 Nm ³ hydrogen per m ³ of feedstock. . 5. The process according to claim 4, wherein the amount of the hydrogen-containing gas stream fed to the reaction section of step a) is such that the hydrogen coverage is between 200 and 300 Nm ³ hydrogen per m ³ of feedstock. 6. The process according to any one of claims 1 to 5, wherein the temperature at the outlet of step a) is at least 30° C. higher than the temperature at the inlet of step a). 7. The method according to any one of claims 1 to 6, comprising at least one fraction of the hydrocarbon-based effluent obtained from said separation step c) or a compound having a boiling point below 175 °C obtained from said fractionation step d). At least one fraction of the naphtha cut is sent to the hydrogenation step a) and/or to the hydrotreating step b). 8. The method according to any one of claims 1 to 7, wherein at least one fraction of the cut comprising compounds having a boiling point greater than 175° C. obtained from the fractionation step d) is selected from the hydrogenation step a) and/or the hydrogen process step b) and/or to said hydrocracking step b'). 9. The process according to any one of claims 1 to 8, comprising a pretreatment step a0) of pretreating the feedstock comprising plastic pyrolysis oil, said pretreatment step being carried out upstream of the hydrogenation step a), filtering step and/or electrostatic separation step and/or washing step with an aqueous solution and/or adsorption step. 10. The method of claim 1 , wherein the hydrocarbon-based effluent obtained from separation step c) or at least one of the two liquid hydrocarbon-based streams obtained from step d) and sent wholly or partly to a steam cracking step e) carried out in at least one pyrolysis furnace at a temperature between 0.05 and 0.3 MPa relative pressure. 11. The process according to any one of claims 1 to 10, wherein the reaction section of step a) uses at least two reactors operating in a permutable mode. 12. The process according to any one of claims 1 to 11, wherein a stream containing amine is injected upstream of step a). 13. The method according to any one of claims 1 to 12, wherein the hydrogenation catalyst comprises a support selected from alumina, silica, silica-alumina, magnesia, clay and mixtures thereof, and at least one Group VIII element and at least one Group VIB element. element, or a hydro-dehydrogenating function comprising at least one Group VIII element. 14. The method according to any one of claims 1 to 13, wherein the hydrotreating catalyst comprises a support selected from the group consisting of alumina, silica, silica-alumina, magnesia, clay and mixtures thereof, and at least one element of group VIII and/or or a hydrogen-dehydrogenating functional group comprising at least one Group VIB element. 15. The method according to any one of claims 1 to 14, wherein n is an integer of 1 or greater, using at least one fixed bed comprising n catalyst layers each containing at least one hydrogen cracking catalyst, Also comprising a second hydrocracking step b″) carried out in the cracking reaction section to obtain a hydrocracked effluent which is sent to the separation step c), said hydrocracking reaction section containing a A cut containing compounds having a boiling point and a gas stream containing hydrogen are supplied, the hydrocracking reaction section having a temperature between 250 and 450° C., a hydrogen partial pressure between 1.5 and 20.0 MPa abs. and an hourly space between 0.1 and 10.0 h ⁻¹ . Used in speed, the way. 16. The method according to any one of claims 1 to 15, wherein the hydrocracking catalyst comprises a support selected from halogenated alumina, a combination of boron and aluminum oxide, amorphous silica-alumina and zeolite, and chromium, molybdenum alone or as a mixture. and a hydrogen-dehydrogenating functional group comprising at least one Group VIB metal selected from tungsten and/or at least one Group VIII metal selected from iron, cobalt, nickel, ruthenium, rhodium, palladium and platinum. . A product obtained by the process according to any one of claims 1 to 16. 18. The method of claim 17, wherein the product, for the total weight of the product,
- a total content of metallic elements of less than or equal to 5.0 ppm by weight;
- a content of elemental iron of not more than 100 ppb by weight;
- a content of elemental silicon of not more than 1.0 ppm by weight;
- a sulfur content of less than or equal to 500 ppm by weight;
- a nitrogen content of less than or equal to 100 ppm by weight;
- a product comprising a content of elemental chlorine of less than or equal to 10 ppm by weight.